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United States Patent |
6,010,161
|
Berg
,   et al.
|
January 4, 2000
|
Plug connection for pressure systems
Abstract
A plug connection for a pressure system comprising a receptacle part and a
plug part, the plug part is inserted into the receptacle part and retained
therein by a locking device which forms a prelocked, unsealed connection
and a locked, sealed connection between the plug part and the receptacle
part with a limit stop element which indicates when the locked, sealed
connection has been obtained.
Inventors:
|
Berg; Manfred (Wipperfurth, DE);
Hagen; Harald (Wipperfurth, DE);
Kaminski; Volker (Halver, DE)
|
Assignee:
|
Armaturenfabrik Hermann Voss GmbH (DE)
|
Appl. No.:
|
872597 |
Filed:
|
June 10, 1997 |
Foreign Application Priority Data
| Jun 14, 1996[DE] | 296 10 496 |
Current U.S. Class: |
285/93; 285/321; 285/910; 285/918; 285/924 |
Intern'l Class: |
F16L 035/00 |
Field of Search: |
285/93,321,924,910,918
|
References Cited
U.S. Patent Documents
2413106 | Dec., 1946 | Kelle | 285/321.
|
3637239 | Jan., 1972 | Daniel | 285/321.
|
3929357 | Dec., 1975 | DeVincent et al. | 295/924.
|
4278276 | Jul., 1981 | Ekman | 285/321.
|
4707000 | Nov., 1987 | Torgardh | 285/924.
|
5662359 | Sep., 1997 | Kargula | 285/93.
|
5681060 | Oct., 1997 | Berg et al. | 285/321.
|
Primary Examiner: Arola; Dave W.
Attorney, Agent or Firm: Jones & Askew
Claims
We claim:
1. A plug connection for pressure systems, comprising:
two coupling parts, a receptacle part (2) and a plug part (4) forming a
plug shaft (6) and seal means carried by one of said parts;
the plug part (4) being insertable into a receptacle opening (8) of the
receptacle part (2) such that the plug shaft (6) is circumferentially
sealed by said seal means relative to the receptacle opening and is
blocked from being separated by means of a locking device (12);
the locking device (12) comprising at least one elastic holding element
(18) arranged in a recess (14) of one coupling part and, in a connected
position of the coupling parts, engaging in locking fashion behind an edge
(16) of the other coupling part;
a limit stop element (20) arranged between the two coupling parts (2, 4) to
apply an axial contact between the coupling parts during insertion of the
plug part (4) so as to cause a noticeable increase, during or shortly
after the connected position is reached, in the coupling force required
for coupling the plug connection;
the limit stop element (20) comprising a ring (24) of elastically
deformable material, the ring being arranged in a radial recess or groove
(26) of one coupling part and cooperating with a step edge (28) of the
other coupling part;
the step edge (28) being arranged between two surface sections (32, 34)
that form an obtuse angle >90.degree.; and
a substantially radially extending projection (36) arranged within the
recess (26) to engage the limit stop element (20) so as to produce an
elastic radial prestress of the limit stop element.
2. Plug connection according to claim 1, characterized in that the limit
stop element (20) is in the form of a O-ring with essentially circular
cross section.
3. Plug connection according to claim 1, characterized in that the locking
device (12) is selectively operable to a completely connected position
which corresponds to the connected position as well as a partially
connected position that corresponds to a prelocked position, wherein the
seal produced by said seal means in the partially connected position is so
incomplete that, an acoustically perceivable leakage noise is generated if
the plug connection is charged with pressure.
4. Plug connection according to claim 1, characterized in that the limit
stop element (20) is arranged within the region between said seal means
(10) that functions as the main pressure seal and the end of the
receptacle opening (8) on the insertion side.
5. Plug connection according to claim 1, characterized in that, in the
connected position, the limit stop element (20) exerts an elastic
prestress force upon the plug part (4) in the separating direction and
thusly compensates axial play of the plug part.
Description
The present invention pertains to a plug connection for pressure systems
which consists of two coupling parts, namely a receptacle part and a plug
part, wherein the plug part can be inserted into a receptacle opening of
the receptacle part in a such a manner that its plug shaft is
circumferentially sealed and the plug part is blocked from being separated
by means of a locking device, and wherein the locking device comprises at
least one elastic holding element that is arranged in a recess of one
coupling part and, in the connected position, engages behind an edge of
the other coupling part in locking fashion.
One example of such a plug connection is known from EP-B-0,005,856. Plug
connections of this type are, for example, used in brake systems for motor
vehicles, in particular, compressed air brake systems for trucks. In this
case--but naturally not only in this case--it is considered problematic
that the assembly personnel frequently does not pay sufficient attention
to producing a correct and complete plug connection, e.g., in case of
unfavorable space conditions or installation situations. Consequently, it
is necessary to carry out test procedures so as to prevent the connection
from suddenly and unintentionally separating once the plug connection is
charged with pressure, e.g., when the brake pressure is built up.
EP-B-0,226,689 discloses a "coupling device;" in order to eliminate the
aforementioned problem, a "prelocking" of the coupling is ensured if a
complete plug connection between the coupling parts is not produced. This
prelocking prevents the connection from being entirely separated once it
is charged with pressure. However, this variation requires an additional
expenditure within the region of the locking device.
The present invention is based on the objective of developing a plug
connection of this type which has a particularly favorable design with
respect to constructive considerations as well as the manufacturing
technology, and significantly reduces the risk of producing faulty plug
connections.
According to the invention, this objective is attained by arranging a limit
stop element between the two coupling parts in a manner such that, during
the insertion of the plug part, a noticeable increase in the coupling
force required for producing the plug connection is caused during or
shortly after the connected position is reached due to the fact that the
lint stop element regionally produces an axial contact between the
coupling parts.
Due to the invention, the assembly person who manually produces the plug
connection perceives this increase in the coupling force to be exerted in
the form of a definite resistance. If the plug connection is produced by
machines, the increase in force could also be determined metrologically
with suitable means. This increase in the coupling force required for
producing the plug connection is a clear indication of the fact that the
connected position, i.e., the interlocking of the plug parts, has actually
occurred, because the increase in force in accordance with the invention
does not occur before the holding element is securely locked.
Consequently, the invention significantly reduces or even entirely
eliminates the risk of producing faulty plug connections, because the
process of producing the plug connection is actually carried out
completely until the "point of a definite increase in force" is reached.
However, if the assembly person completes the process of manually producing
the plug connection before the connected position according to the
invention is reached, i.e., before the aforementioned increase in the
coupling force occurs, it may be advantageous to design the locking device
in a manner such that a fully locked position which corresponds to the
previously described connected position as well as a prelocked position
which corresponds to a partially connected position are ensured. In this
case, it is preferred--essentially in accordance with the initially
mentioned EP-B-0,226,689--that a signal, in particular, in the form of an
acoustically perceivable leakage noise, be generated by the incomplete
seal produced in the partially connected position if the plug connection
is charged with pressure. Naturally, a complete and pressure-tight seal is
produced in the fully locked position. In this case, the aforementioned
signal is an indication of the fact that an incorrect plug connection has
been produced, i.e., the respective coupling parts can be further inserted
into one another until the fully locked position is reached. However,
completely separation of the coupling parts from one another can be
prevented. In this preferred embodiment of the plug connection with "two
locking positions" or a "double lock," the limit stop element according to
the invention is designed in a manner such that the "point of a definite
increase in force" occurs in or shortly behind the fully locked position,
because this position corresponds to the connected position.
According to the invention, it is particularly advantageous to design the
limit stop element elastically such that am "elastic limit stop" is
ensured; due to the unavoidable manufacturing tolerances, a "rigid limit
stop" could only be realized with high expenditures.
Additional advantageous characteristics of the invention are and explained
in detail in the following description.
Preferred embodiments of the invention are described in detail below with
reference to the figures. The figures show:
FIG. 1, a partial axial section through a plug connection according to the
invention with two locking positions, in which the fully locked position
is illustrated in the left half of the figure (FIG. 1a) and the prelocked
position is illustrated in the right half of the figure (FIG. 1b), and
FIG. 2, a simplified schematic diagram of the coupling force in dependence
on the insertion path.
FIG. 1 shows that the plug connection according to the invention consists
of a receptacle part 2 and a plug part 4. The plug part 4 comprises a plug
shaft 6 that can be inserted into a receptacle opening 8 of the receptacle
part 2 such that the plug shaft is sealed relative to the receptacle
opening 8 by means of at least one circumferential seal 10 and blocked
from being separated in the fully connected position by means of a locking
device 12 (see FIG. 1a).
The locking device 12 comprises at least one radially elastic holding
element 18 that is arranged in a recess 14 of one coupling part, namely in
the recess 14 of the receptacle part 2 which is realized in the form of an
inner annular groove in the embodiment shown, and, in the connected
position, engages behind an edge 16 of the other coupling part, i.e., the
plug part 4, in positively locking fashion.
According to the invention, a limit stop element 20 is arranged between the
two coupling parts 2, 4 in a manner such that, during the insertion of the
plug part 4 (in the direction of the arrow 22 in FIG. 1), a noticeable
increase in the coupling force F required for producing the plug
connection is caused no earlier than or shortly after reaching the
connected position (FIG. 1a) due to the fact that the limit stop element
20 regionally produces an axial contact between the coupling parts 2, 4.
In this case, the limit stop element 20 is preferably realized
elastically, i.e., the limit stop according to the invention pertains to
an "elastic limit stop."
FIG. 2 shows a diagram of the coupling force F required for producing the
plug connection in dependence on the insertion path S. This diagram is
highly schematic with respect to the fact that all changes in the coupling
force F caused by the locking device or the sealing elements are not
illustrated in the characteristic. Starting at the point of origin, the
coupling force is initially increased to a "normal" coupling force F.sub.N
when the plug shaft 6 is inserted into the receptacle opening 8 of the
receptacle part 2. Once the required lock is produced in the locked
position S.sub.R, the force F is suddenly increased, namely in dependence
on the elasticity of the limit stop element 20 according to the invention,
i.e., in accordance with the respective spring characteristic of the
elastic limit stop element 20. This increasing characteristic may,
starting at the point S.sub.R, be realized nearly arbitrarily by
correspondingly selecting the material and/or the shape, in particular,
the cross section, of the limit stop element 20 and/or by correspondingly
designing the contact region between the two coupling parts 2, 4. Examples
of this aspect are indicated in FIG. 2 by different characteristics drawn
in broken lines.
It is preferred that the limit stop element 20 be realized in the form of a
ring 24 that consists of an elastically deformable material. This ring is
situated in a radial recess of one coupling part, in particular, in an
outer annular groove 26 of the plug part 4, and cooperates with a step
edge 28 of the other coupling part, in particular, with a step edge 28 of
the receptacle part 2 which reduces the cross section of the receptacle
opening 8. This means that the limit stop element 20 is axially "clamped"
between a contact surface 30 that limits the outer annular groove 26 and
the step edge 28 in the connected position (FIG. 1a). In this case, it is
possible to exactly define or control the increase in the coupling force
according to the invention, e.g., by correspondingly shaping the step edge
28. In the preferred embodiment shown, the step edge 28 is arranged
between two conical surface sections 32, 34 that, in particular, form an
obtuse angle .alpha.>90.degree.. Consequently, the limit stop element 20
is also radially compressed to a certain degree during its axial
compression, i.e., the increase in the coupling force can be influenced.
The increase in the coupling force can also be influenced by a special
design of the recess that accommodates the limit stop element 20, i.e.,
the other annular groove 26 of the plug part 4 shown in the figure. The
figure indicates that an essentially radially extending projection 36, in
particular, a radial projection in the form of an annular web, may be
arranged within the recess or outer annular groove 26, namely such that an
elastic prestress is attained due to a certain radial widening of the
limit stop element 20. This measure ensures a rigid, secure seat of the
limit stop element 20 in the outer annular groove 26. The radial
projection 36 or annular web is preferably arranged approximately within
the central region of the outer annular groove 26 of the plug part 4. In
this case, the limit stop element 20 is preferably realized in the form of
a conventional O-ring with essentially circular cross section.
The latter described embodiment is particularly advantageous in combination
with a special embodiment of the locking device 12, in which the locking
device 12 ensures a completely connected or fully locked position that
corresponds to the previously described connected position (FIG. 1a) as
well as a prelocked position that corresponds to a partially connected
position. In the partially connected position, the seal produced is
preferably so incomplete that, if the plug connection is charged with
pressures a signal, in particular, in the form of an acoustically
perceivable leakage noise, is generated. Naturally, a complete and
pressure-tight seal is produced in the fully locked position. This means
that a defined leakage flow occurs in the partially connected or prelocked
position (FIG. 1b). In this case, the previously described measure for
generating an elastic radial prestress of the limit stop element 20 is
particularly advantageous with respect to the fact that--due to the
elastic widening of the ring 24--the ring 24 is secured from being "blown
out" or "washed out" of the outer annular groove 26.
Concrete constructive measures for such an embodiment of the locking device
12 which also ensure a prelocked position of the plug components are--in
addition to the initially cited EP-B-0,226,689--also described in numerous
older applications of the applicant. For example, we refer to German
Patent Application No.s 19,522,052.8, 19,523,830.3, 19,523,831.1 and
19,523,833.8 in their entirety. These applications respectively attain a
"double-locking effect" due to the positive engagement of a catch element.
In addition, we refer to a German application with the internal
representative file No. 7947 which discloses a prelocking effect that, in
particular, is attained due to a positive or positive/nonpositive
connection.
The embodiment of the locking device 12 shown in the figures corresponds to
the embodiment according to German Patent Application No. 19,621,535.8. In
this case, the holding element 18 consists of a carrier element 38
situated in the recess 14 and two catch elements 40, 42 that are held in
the carrier elements 38 in elastically deformable fashion and arranged
axially behind one another, namely such that one catch element 42 engages
behind the edge 16 in the prelocked position--see FIG. 1b--and the other
catch element 40 engages behind said edge in the fully locked
position--see FIG. 1a. Regarding additional details, we refer to the
aforementioned application in its entirety.
If a prelocked position according to FIG. 1b is provided, it is
advantageous to protect the main circumferential seal 10 from being "blown
out" by the defined leakage flow. Concrete measures regarding this aspect
are disclosed in the older patent application No. 19,536,333.7 of the
applicant. This embodiment shows that the circumferential seal 10 is
realized in a manner such that it already radially adjoins the inner
surface of the receptacle opening 8 in the prelocked position via
circumferentially distributed contact points 44 that are spaced apart from
one another. Axial leakage gaps are formed in the circumferential
direction between the respective contact points 44. The circumferential
seal 10 preferably consists of a profiled elastic ring that is divided
into two axially adjacent regions, namely into a sealing region with an
annular cross section that is essentially constant over the entire
circumference as well as a leakage region consisting of contact sections
and radial recesses that for the leakage gaps. These contact sections and
radial recesses alternately form the contact points 44 in the
circumferential direction. The aforementioned application also discloses
other alternatives; i.e., we hereby refer to this application in its
entirety.
It is advantageous to arrange the limit stop element 20 or the ring 24
within the region between the main circumferential seal 10 and the end of
the receptacle opening 8 on the insertion side. Due to this measure, the
elastic ring 24 additionally acts as a seal against the admission of dirt,
moisture and the like, e.g., as a so-called "dust seal", in the fully
locked position according to FIG. 1a. In addition, the elastic limit stop
element 20 advantageously compensates or prevents an axial play of the
plug part 4 in the connected position (FIG. 1a) because the limit stop
element exerts a prestress force (spring force) upon the plug part 4 in
the separating direction, i.e., the plug part 4 is always held in contact
with the receptacle part 2 via the holding element 18.
It should also be mentioned that it is preferred to realize the receptacle
part 2 from two separate parts that are connected to one another in
separable fashion in order to simplify the removal of the plug part 4 that
is locked in position by the locking device 12. The receptacle part
consists of a base part 2a and an insert part 2b that is preferably
realized in the form of a male fitting. After removing the insert part 2b
from the base part 2a, the plug part 4 can be removed together with part
of the locking device 12, i.e, the holding element 18, and the insert part
2b.
The invention is not limited to the embodiments shown and described, but
also includes all embodiments that function identically in the sense of
the invention.
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